import java.util.Scanner;
// 1:无需package
// 2: 类名必须Main, 不可修改

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int[] arr = new int[10000007];
        int index = 1;
        for(int i = 1; i < 10000007; i++){
            for(int j = 1; j <= index; j++){
                arr[i] = index;
            }
            index++;
        }
        System.out.println(arr[n]);
        scan.close();
    }
}